NEREIS (ALITTA) VIKENS. 333 



The first foot (Plate LXXIII, fig. 2) has (in spirit) a short and somewhat thick dorsal 

 cirrus, the tip of which does not reach that of the dorsal lobe. The latter is lanceolate, 

 slightly contracted at the base in lateral view, and tapering to a blunt tip. The 

 setigerous process is attached to the anterior face of the second lobe so that only the tips 

 of the bristles project beyond it, and nothing is seen of the process itself from behind. 

 These bristles all have slender, tapering, finely spinous tips (Plate LXXXL, fig. 7, a,b, c) 

 and slightly camerated shafts. The middle lobe is tongue-shaped in lateral view, and its 

 blunt tip projects further than that of the dorsal lobe. The ventral lobe is closely 

 united at its base with the middle lobe, and its vertical diameter is greater in the free 

 region. Its blunt tip scarcely projects as far as that of the former. The ventral cirrus 

 arises close beneath, and its tip does not reach, by a larger interval than in the case of 

 the dorsal, the tip of the ventral lobe. 



The third foot, as in other Nereids, has two setigerous lobes, and the lamellae, 

 especially the dorsal, are somewhat longer. The fourth foot shows a decided increase in 

 the dorsal lamella and in the space between it and the body, and these points continue to 

 increase until at the tenth foot (Plate LXXIII, fig. 2 a) — by the development of these 

 parts in breadth and depth — a large foliaceous lobe is formed with the dorsal cirrus 

 amalgamated and chiefly visible on the posterior border. The superior setigerous lobe 

 forms an ovate process in front of the bristles, the tongue-shaped middle lobe, which 

 projects considerably further, being fused with it inferiorly. A gap exists between the 

 foregoing and the inferior setigerous lobe, which has a free lanceolate lamella at its upper 

 and posterior edge. In front of this the setigerous lobe proper is bifid, with a small 

 upper and a larger inferior papilla from which the tip of the spine projects in front of 

 the bristles. The groups of bristles correspond to the ordinary types, but all have 

 simple tapering tips, the inferior group (corresponding to the heterogomph series) 

 having decidedly shorter tips. All the tips of the bristles are finely serrated and have 

 cameras in the shafts, except a small portion at the base and distal end. The ventral 

 cirrus arises from an elevation on the ventral surface and does not reach the middle of 

 the ventral lobe. 



The development of the superior lamella continues behind the tenth foot, and the 

 dorsal cirrus becomes more and more lamellar in position, so that in the region of the 

 thirty-seventh foot (Plate LXXIII, fig. 2 b) the maximum is reached. It is true that at 

 the fifty-seventh foot the lamella is proportionally larger, but the foot generally is 

 considerably less. The second lamella is also thin and foliaceous (lanceolate), especially 

 after the anterior third. In life large pale wart-like papillae occur on the edge of the 

 dorsal lamella. The dorsal and ventral cirri show no blood-vessels, and no cilia, but 

 palpocils occur at the tip of both. 



In front of the tail (twelfth bristled foot from the tip) the dorsal lamella still retains 

 its characteristic foliaceous form, the cirrus is longer and more slender, though its tip 

 does not reach that of the lamella. It arises from a slight notch of the dorsal edge of the 

 lamella about its middle. The foot is thinner and more flattened, so that the setigerous 

 papillae are brought into the vertical line of the edge, and thus do not possess the more 

 complex arrangement they have in front. The tips of the lobes below the dorsal are also 

 more pointed. The ventral cirrus remains short. 



